Neuropathology Flashcards
**REFER TO NOTES FOR IMAGES***
This question is about cerebrospinal fluid.
How much is normal?
Where is it produced and reabsorbed?
What is its metabolic importance?
Where is it circulated?
Normal volume 150ml
Produced by choroid plexus in the lateral ventricles (500ml every 24 hours)
Reabsorbed by arachnoid granulations in the subarachnoid space
Metabolic importance:
- Cushioning of the CNS
- Role in immune regulation and defence
- Cerebral autoregulation
Circulated through the lateral ventricles –> interventricular formamen–> third ventricle –> cerebral aqueduct –> fourth ventricle –> central canal
Define and explain the causes of hydrocephalus
A condition in which there is an accumulation of CSF in the brain. (Very rarely OVERproduction)
- COMMUNICATING: aka non-obstructive hydrocephalus, is caused by impaired cerebrospinal fluid reabsorption in the absence of any CSF-flow obstruction between the ventricles and subarachnoid space
- NON COMMUNICATING: there is a physical block
- Very rarelt due to overproduction of CSF
!Leads to shrinking of brain tissue (as in dementia)= ex vacuo
-If it occurs before fusion of cranial sutures it causes enlargement of the head circumference
What is considered raised intracranial pressure?
Causes?
Means CSF pressure > 200mm H2O
Causes:
- Increased CSF volume (hydrocephalus)
- Intracranial space occupying lesion (neoplasm, haemorrhage, abscess)
- Cerebral oedema (can be vasogenic-increased vascular permeability or cytotoxic- neuronal, glial or endothelial cell damage)
What are the types of herniation?
Subfalcial (cingulate)
Central/transtentorial
Tonsillar/cerebellar - can cause compression of the medulla with impairment of vital respiratory and cardiac functions
Which kind of haemorrhages may be classified as space-occupying lesions?
What other space occupying lesions are there?
Extradural/epidural haemorrhage
Subdural haemorrhage
Subarachnoid haemorrhage
Intracerebral haemorrhage
Ischaemic infarct (stroke) with subsequent oedema or haemorrhage
Neoplasm
Abscess
What kinds of head trauma can occur?
Skull fracture
Vascular injury
Coup injury (injury on side of impact)
Contrecoup injury (injury on opposite side of impact)
Parenchymal injury e.g. contusion (bruising), laceration (penetration or tearing), diffuse axonal injury
Consider vascular injury
What kind of injury is most likely to cause an extradural hemorrhage?
Which vessel is most likely to be ruptured?
Symptoms?
CT appearance?
Severe trauma with arterial laceration
Middle meningeal artery (following break of temporal bone, particularly pterion)
Often there is loss of consciousness following a head injury, a brief regaining of consciousness, and then loss of consciousness again. Other symptoms may include headache, confusion, vomiting, and an inability to move parts of the body. Complications may include seizures
Biconvex appearance (semi circle)
Consider vascular injury
What kind of injury is most likely to cause a subdural hemorrhage?
Which vessel is most likely to be ruptured?
Symptoms?
CT apperance?
Trauma may be minor in atrophy
Bridging veins which cross the subdural space
Slower onset, gradually increasing headache and confusion
Crescent appearance
Consider vascular injury
What kind of injury is most likely to cause a subarachnoid hemorrhage?
Which vessel is most likely to be ruptured?
Symptoms?
CT appearance?
Rupture of saccular (berry) aneurysm
Circle of Willis
Severe headache of rapid onset, vomiting, decreased level of consciousness, fever, and sometimes seizures and neck stiffness
Fluid in ventricles
Consider vascular injury
What is an intraparenchymal haemorrhage?
What kind of injury is most likely to cause an intraparenchymal hemorrhage?
A type of intracerebral bleed. It is within the actual brain tissue. The other type is intraventricular.
Hypertension
State the distribution of berry aneurysms on circle of Willis?
40% on anterior communicating artery
20% on posterior communicating artery
34% middle cerebral artery
4% basilar artery
How much of the hearts CO and O2 is relayed to the brain?
What kinds of stroke are there?
15% of CO and 20% of O2 demand (neurons are the most oxygen sensitive cells)
In a stroke there is a SUDDEN onset of neurological symptoms
Can be hypoxia or ischaemia (global vs focal)
Haemorrhagic infarction in emboli (petechial lesions e.g. BM)
Ischaemic infarction in thrombosis
What is typical of the histology of stroke?
Ren neurons Pyknosis of nucleus Shrinkage of the cell body Loss of nucleoli Intense eosinophilia of cytoplasm
**Owing to irreversible hypoxic/ischaemic insult
Are neoplasms likely to be primary or metastatic?
How frequent are they in children?
Where do they originate?
75% are primary, the rest metastatic
20% of malignant childhood tumours are located in the CNS
Gliomas (astrocytoma, oligodendroglioma, glioblastoma)
Neural tumours (ganglion cell tumours)
Meningiomas
Poorly differentiated neoplasms (medullablastoma)
Primary CNS lymphoma
Metastasis (lung, breast, skin/melanoma, kidney, GI tract)
Peripheral nerve tumours (schwanoma, neurofibroma, MPNST)
What are the commonest causes of meningitis in:
New borns
Children
University students
Adults/The elderly
Immunocompromised?
Other?
Newborns: Group B Streptococcus, Strept. pneumoniae, Listeria monocytogenes, E.coli
Babies and children: Strept. pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b (Hib), group B Streptococcus
Teens and young adults: Neisseria meningitidis, Strept. pneumoniae
Older adults: Streptpneumoniae, Neisseria meningitidis, Haemophilus influenzae type b (Hib), group B Streptococcus, Listeria monocytogenes
Immunocompromised: viral menigitis (HIV, enterovirus`), Candida fungus, parasites (toxicoycisis from pets)
RMSV, Neurosyphilis, lyme disease, malaria
